FDNY Z51 WRITTEN EXAM UPDATED

• | Page

FDNY Z51 WRITTEN EXAM UPDATED

ACTUAL EXAM WITH CORRECT SOLUTIONS.

The efficiency of the refrigerant cycle is affected by the operation of the condenser. of the following. a more efficient

centrifugal compressor operation results from: - correct answer-

Lowering the condensing pressure

The heat removed from the refrigerant in a condenser is: -

correct answer- Sensible and latent heat

The refrigerant unit that you have been assigned to is being taken out of service for a major repair. you have been assigned to withdraw refrigerant for storage in suitable containers.according to the new York city fire code, you must ensure that

the containers: - correct answer- Are approved by the US

department of transportation

Which of the following best describes how the cylinder unloader work? - correct answer- Keep in the suction valve opened while the compressor is in the return stroke

• / 4

• | Page

In most semi hermetic compressors, the suction vapor is used

to: - correct answer- Cool the motor

The amount of refrigerant that flows through the orifices of a

economizer is determined by the: - correct answer- Difference

between the high side and load side pressure

The installation of an inline refrigerant cleaning system is

advisable: - correct answer- To remove impurities from the

system

The type of refrigerant system that is least likely to leak refrigerant into the building space that are cooled - correct answer- The indirect system

The suction pressure of a reciprocating compressor is 65PSIG.the discharge pressure of this compressor is 120PSIG. the atmospheric is 14.7 PSI. the compression ratio for the given

condition is closet to: - correct answer- 1.69

A super heated vapor is a ? - correct answer- Dry vapor above the saturation temperature

• / 4

• | Page

A refrigerant engineer verifies that a condenser water pump is cavitating. of the following the most likely cause for this

condition is: - correct answer- A faulty cooling tower water level

controller

A centrifugal water pump is known as a lift pump when the: -

correct answer- The water supply to the pump suction inlet is below the pump level

A TXV is used to maintain constant: - correct answer-

Evaporator superheat

The chilled water supply to the building is 55F. if the chiller is being used for human comfort, should you be concerned about this , and why? - correct answer- Yes, this temperature is too high for human comfort purpose

The packing gland of a centrifugal pump serves to: - correct

answer- The drip part of the packing gland gives evidence that there is water in the pump

• / 4

• | Page

Capacity control of a reciprocating hermetic compressor is typically achieved through - correct answer- Operation of the hot gas bypass valve

The most important reason to sub-cool the refrigerant in the

condenser is to ensure that: - correct answer- A pure liquid

refrigerant will enter the metering device

A refrigeration engineer is logging reading from a reciprocating system. compressor discharge temperature have dropped significantly and the suction line pressure is high. which of the following that may be causing this set of condition. - correct answer- An expansion valve that is open to wide

A low side float valve is used to maintain: - correct answer- The

level of the refrigerant in the evaporator

Regarding fire safety, which ASHARE refrigerant safety classification indicates no flammability and lower the toxicity? - correct answer- A1

When an expansion valve is operating properly, at the end of

the evaporator will contain: - correct answer- Only superheated

vapor

• / 4